1. Field of the Invention
The invention relates to a wire-stranded medical hollow tube in which a plurality of metallic wires are twisted along a circular line to be shaped into a coreless hollow configuration, and particularly concerns to a medical tube body and a medical guide wire into which the wire-stranded medical hollow tube is incorporated.
2. Description of Prior Art
As a general medical tube body, a synthetic resin tube and a flexible tube (T) has been introduced in which a helical spring (S) is embedded in a synthetic resin (P) as shown in FIG. 34. The helical spring (S) is single wound or multiple wound by a spring forming machine. To take a five-turn wound helical spring (U) as an example in FIG. 35, a gap (G) is likely to appear at every five-turn wound end (N). The gap (G) develops remarkably in particular when an initial winding tension is not enough upon forming the helical spring (u).
This not only imparts the helical spring (U) with a convexso-concave outer appearance but result in a loss of torque under the presence of the gap (G) when transmitting the torque through the helical spring (U). An accumulated loss of the torque exceedingly reduces the torque transmissibility. On the other hand, the helical spring (U) increases its rigidity when the initial winding tension is strengthened too much upon forming the helical spring (U). Under the increased rigidity, the frictional resistance increases between the helical spring (U) and an inner wall of a wound and small blood vessel every time when advancing the helical spring (U) to pass through wound portions of the wound and small blood vessel. The increased frictional resistance deteriorates a manipulatability when the helical spring (U) is applied to a medical guide wire.
A Laid-open Japanese Patent Application No. 11-25758 (prior reference) discloses a wire-stranded hollow body in which wire elements are twisted along a circle line to overcome the drawbacks which a multiple coaxial cable wire usually has, so as to attain a lightweight structure with a smooth surface and a good circularity. The wire-stranded hollow body disclosed by the prior reference, however, is applied practically to an electric cable wire and has no substantial suggestion about an improved tightness between the wire elements to ensure a quick torque response and a good torque transmissibility.
Therefore, the present invention has been made with the above disadvantages in mind, it is a main object of the invention to provide a medical tube body and a medical guide wire which has a wire-stranded hollow tube formed by a plurality of metallic wires twisted along a circular line into a coreless hollow configuration with no gap appeared between the neighboring metallic wires by increasing a contact pressure therebetween to attain a good tightness between the neighboring metallic wires with a good circularity and a good diametrical uniformity to ensure a quick torque response and good torque transmissibility with the least play, thereby leading to a good manipulatability with a favorable follow-on capability.